<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .con {
            width: 300px;
            height: 300px;
            border: 1px solid #000;
        }

        .con .div1 {
            width: 70px;
            height: 70px;
            background-color: gold;
            /*浮动会把元素 转为内联块  没有间隙*/

          
        }

        .con .div2 {
            width: 70px;
            height: 70px;
            background-color: red;
            float: left;
        }

        .con .div3 {
            width: 80px;
            height: 80px;
            background-color: blue;
              float: left;
        }
    </style>
</head>

<body>


    <div class="con">
        <div class="div1">1</div>
        <div class="div2">2</div>
        <div class="div3">3</div>
    </div>



</body>

</html>